Method of using an orthopaedic instrument system in surgically-preparing a patient&#39;s femur

ABSTRACT

An orthopaedic joint replacement system is shown and described. The system includes a number of prosthetic components configured to be implanted into a patient&#39;s knee. The system also includes a number of surgical instruments configured for use in preparing the bones of the patient&#39;s knee to receive the implants. A method or technique for using the surgical instruments to prepare the bones is also disclosed.

The present application claims priority under 35 U.S.C. § 119 to U.S.Patent Application Ser. No. 62/338,468, filed May 18, 2016, and havingthe title “SYSTEM AND METHOD FOR PREPARING A PATIENT'S BONE TO RECEIVE APROSTHETIC COMPONENT,” which is herein incorporated by reference in itsentirety.

CROSS-REFERENCE TO RELATED APPLICATIONS

Cross reference is made to U.S. Patent Application Ser. No. 62/338,276entitled “SYSTEM AND METHOD FOR PREPARING A PATIENT′S FEMUR IN ANORTHOPAEDIC JOINT REPLACEMENT PROCEDURE;” and U.S. Patent ApplicationSer. No. 62/338,284 entitled “SYSTEM AND METHOD FOR PREPARING APATIENT'S TIBIA IN AN ORTHOPAEDIC JOINT REPLACEMENT PROCEDURE,” each ofwhich is assigned to the same assignee as the present application, eachof which is filed concurrently herewith, and each of which is herebyincorporated by reference.

Cross reference is made to U.S. patent application Ser. No. 15/598,619entitled “ORTHOPAEDIC INSTRUMENT SYSTEM FOR SURGICALLY-PREPARING APATIENT'S FEMUR”, which is assigned to the same assignee as the presentapplication, which is filed concurrently herewith, and which is herebyincorporated by reference.

TECHNICAL FIELD

The present disclosure relates generally to an orthopaedic prosthesissystem, including prosthetic components and instruments for use in theperformance of an orthopaedic joint replacement procedure, and moreparticularly to orthopaedic prosthetic components and surgicalinstruments for use in the performance of a knee replacement procedure.

BACKGROUND

Joint arthroplasty is a well-known surgical procedure by which adiseased and/or damaged natural joint is replaced by a prosthetic joint.For example, in a total knee arthroplasty surgical procedure, apatient's natural knee joint is partially or totally replaced by aprosthetic knee joint or knee prosthesis. A typical knee prosthesisincludes a tibial tray, a femoral component, and a polymer insert orbearing positioned between the tibial tray and the femoral component.The tibial tray generally includes a plate having a stem extendingdistally therefrom, and the femoral component generally includes a pairof spaced apart condylar elements, which include surfaces thatarticulate with corresponding surfaces of the polymer bearing. The stemof the tibial tray is configured to be implanted in asurgically-prepared medullary canal of the patient's tibia, and thefemoral component is configured to be coupled to a surgically-prepareddistal end of a patient's femur

From time-to-time, a revision knee surgery may need to be performed on apatient. In such a revision knee surgery, the previously-implanted kneeprosthesis, sometimes referred to a “primary knee prosthesis,” issurgically removed and a replacement or revision knee prosthesis isimplanted. In some revision knee surgeries, all of the components of theprimary knee prosthesis, including, for example, the tibial tray, thefemoral component, and the polymer bearing, may be surgically removedand replaced with revision prosthetic components. In other revision kneesurgeries, only part of the previously-implanted knee prosthesis may beremoved and replaced.

During a revision knee surgery, the orthopaedic surgeon typically uses avariety of different orthopaedic surgical instruments such as, forexample, cutting blocks, surgical reamers, drill guides, prosthetictrials, and other surgical instruments to prepare the patient's bones toreceive the knee prosthesis. Other orthopaedic surgical instruments suchas trial components may be used to size and select the components of theknee prosthesis that will replace the patient's natural joint. Trialcomponents may include a femoral trial that may be used to size andselect a prosthetic femoral component, a tibial tray trial that may beused to size and select a prosthetic tibial tray, and a stem trial thatmay be used to size and select a prosthetic stem component.

SUMMARY

An orthopaedic joint replacement system is shown and described. Thesystem includes a number of prosthetic components configured to beimplanted into a patient's knee. The system also includes a number ofsurgical instruments configured for use in preparing the bones of thepatient's knee to receive the implants. A method or technique for usingthe surgical instruments to prepare the bones is also disclosed.

According to one aspect of the disclosure, an orthopaedic surgicalinstrument system includes a femoral cutting block including a pluralityof cutting guide slots and an offset guide. The offset guide includes amounting bracket configured to be coupled to the femoral cutting block.The mounting bracket has a distal surface and an opening defined in thedistal surface. The offset guide also includes an adaptor bodypositioned in the opening defined in the mounting bracket. The adaptorbody extends along a first longitudinal axis and includes a head platethat is pivotally coupled to the mounting bracket. The offset guide alsoincludes an elongated shaft pivotally coupled to the adaptor body. Theelongated shaft extends along a second longitudinal axis spaced apartfrom the first longitudinal axis. An intramedullary orthopaedic surgicalinstrument is configured to be coupled to the elongated shaft and sizedto be inserted into a medullary canal of a patient's femur.

In some embodiments, the elongated shaft may have a triangular-shapedconnector. The intramedullary orthopaedic surgical instrument may havean opening sized to receive the triangular-shaped connector of theelongated shaft. In some embodiments, the intramedullary orthopaedicsurgical instrument may have a stem stabilizer configured to be coupledto the elongated shaft. A stem trial may be configured to be coupled tothe stem stabilizer.

In some embodiments, the distal surface of the mounting bracket maydefine a first plane. The first longitudinal axis may extend at anoblique angle relative to the first plane. In some embodiments, the headplate may have a distal surface that defines a second plane that extendsat an oblique angle relative to the first plane and may be orthogonal tothe first longitudinal axis.

In some embodiments, a positioning block may have a main body, a firstarm extending outwardly from the main body, and a second arm extendingoutwardly from the main body parallel to, and spaced apart from, thefirst arm. The cutting block may have a mounting slot sized to receive atip of the first arm to couple the positioning block to the cuttingblock.

In some embodiments, an offset indicator may have a plug sized to bereceived in an aperture defined in the head plate of the adaptor body.The offset indicator may have a plurality of visual indicia to indicatean offset orientation of a prosthetic femoral component assembly. Theoffset indicator may be operable to pivot the head plate relative to themounting bracket. In some embodiments, the mounting bracket may have avisual indicator configured to be aligned with at least one of theplurality of visual indicia of the offset indicator to indicate aplanned offset orientation of a prosthetic femoral component. In someembodiments, the plug may have an alignment tab. The head plate may havean alignment slot sized to receive the alignment tab to position theoffset indicator in a predetermined orientation relative to the offsetguide.

In some embodiments, a surgical handle may have a locking flangepivotable between a locked position and an unlocked position. The headplate of the offset guide may have an annular rim sized to receive thelocking flange to secure the surgical handle to the offset guide.

According to another aspect of the disclosure, an orthopaedic surgicalinstrument system includes a mounting bracket configured to be coupledto a femoral cutting block. The mounting bracket has a distal surfaceand an opening defined in the distal surface. An adaptor body ispositioned in the opening defined in the mounting bracket. The adaptorbody extends along a first longitudinal axis and includes a head platethat is pivotally coupled to the mounting bracket. An elongated shaft ispivotally coupled to the adaptor body. The elongated shaft extends alonga second longitudinal axis spaced apart from the first longitudinal axisand includes a connector at its proximal end. A sleeve is positioned onthe elongated shaft between the adaptor body and the connector. Anintramedullary orthopaedic surgical instrument is coupled to theconnector of the elongated shaft and sized to be inserted into amedullary canal of a patient's femur. The sleeve is movable along theelongated shaft between (i) a first position in which the sleeve engagesthe intramedullary orthopaedic surgical instrument to secure theintramedullary orthopaedic surgical instrument to the elongated shaft,and (ii) a second position in which the sleeve is spaced apart from theintramedullary orthopaedic surgical instrument.

In some embodiments, the connector may be triangular-shaped. Theintramedullary orthopaedic surgical instrument may have an opening sizedto receive the triangular-shaped connector. In some embodiments, thesleeve may have a threaded outer surface and the intramedullaryorthopaedic surgical instrument may have a threaded inner surface thatengages the threaded outer surface when the sleeve is in the firstposition. In some embodiments, the opening of the intramedullaryorthopaedic surgical instrument may have a plurality of slots defined inthe threaded inner surface of the intramedullary orthopaedic surgicalinstrument.

In some embodiments, the intramedullary orthopaedic surgical instrumentmay have a stem stabilizer coupled to the connector of the elongatedshaft.

In some embodiments, an offset indicator may be configured to be coupledto the adaptor body. The offset indicator may have a plurality of visualindicia to indicate an offset orientation of a prosthetic femoralcomponent assembly. The offset indicator may be operable to pivot thehead plate and the adaptor body relative to the mounting bracket.

According to yet another aspect of the disclosure, an orthopaedicsurgical instrument system includes an offset guide. The offset guideincludes a mounting bracket configured to be coupled to a femoralcutting block. The mounting bracket has a distal surface and an openingdefined in the distal surface. An adaptor body is positioned in theopening defined in the mounting bracket. The adaptor body extends alonga first longitudinal axis and includes a head plate that is pivotallycoupled to the mounting bracket. An elongated shaft is pivotally coupledto the adaptor body. The elongated shaft extends along a secondlongitudinal axis spaced apart from the first longitudinal axis andincludes a connector sized to receive an intramedullary orthopaedicsurgical instrument. An offset indicator is configured to be coupled tothe head plate of the adaptor body. The offset indicator includes aplurality of visual indicia to indicate an offset orientation of aprosthetic femoral component assembly. When the elongated shaft isprevented from rotating about the second longitudinal axis, the offsetindicator is operable to pivot the head plate relative to the mountingbracket about the first longitudinal axis and pivot the head platerelative to the elongated shaft about the second longitudinal axis.

In some embodiments, the offset guide also may have a sleeve positionedon the elongated shaft. The sleeve may be movable along the elongatedshaft between a first position in which a threaded section of the sleeveengages the intramedullary orthopaedic surgical instrument to secure theintramedullary orthopaedic surgical instrument to the elongated shaft,and a second position in which the sleeve may be spaced apart from theintramedullary orthopaedic surgical instrument. In some embodiments, theconnector may be triangular-shaped.

In some embodiments, the offset indicator may have an alignment tab. Thehead plate may have an alignment slot sized to receive the alignment tabto position the offset indicator in a predetermined orientation relativeto the offset guide.

According to an aspect of the disclosure, a method of performing anorthopaedic surgical procedure includes aligning a distal end of anintramedullary orthopaedic surgical instrument with a proximal end of anoffset guide. The method also includes positioning a connector at theproximal end of the offset guide in an opening defined in the distal endof the intramedullary orthopaedic surgical instrument to preventrelative rotational movement between the proximal end of the offsetguide and the intramedullary orthopaedic surgical instrument. The methodalso includes advancing the intramedullary orthopaedic surgicalinstrument over the connector. The method also includes engaging asleeve with the intramedullary orthopaedic surgical instrument to securethe intramedullary orthopaedic surgical instrument to the offset guide.

In some embodiments, engaging the sleeve with the intramedullaryorthopaedic surgical instrument may require advancing the sleeve towardthe proximal end of the offset guide and engaging a threaded outersurface of the sleeve with a threaded inner surface of theintramedullary orthopaedic surgical instrument. In some embodiments,positioning the connector at the proximal end of the offset guide in theopening defined in the distal end of the intramedullary orthopaedicsurgical instrument may require positioning a triangular-shapedconnector into a plurality of slots defined in the threaded innersurface of the intramedullary orthopaedic surgical instrument.

In some embodiments, the method may require securing a stem stabilizerto a stem trial to form the intramedullary orthopaedic surgicalinstrument.

In some embodiments, the method may require inserting the intramedullaryorthopaedic surgical instrument into an opening defined in a distal endof a patient's femur. The method may require rotating a distal end ofthe offset guide about a longitudinal axis extending through theintramedullary orthopaedic surgical instrument to determine an offsetorientation for a prosthetic femoral component. In some embodiments, themethod may require securing the distal end of the offset guide to afemoral cutting block including a plurality of cutting slots. Rotatingthe distal end of the offset guide may require rotating the femoralcutting block relative to a distal surface of the patient's femur. Insome embodiments, the method may require attaching an offset indicatorto the distal end of the offset guide. Rotating the distal end of theoffset guide may require rotating the offset indicator about a secondlongitudinal axis extending parallel to, and spaced apart from, thelongitudinal axis extending through the intramedullary orthopaedicsurgical instrument.

In some embodiments, the method may require attaching a first arm of afemoral positioning block to the cutting block. The method may requirepositioning a second arm of the femoral positioning block on a proximalend of the patient's tibia such that a predetermined gap may be definedbetween the patient's tibia and the femoral cutting block. Rotating thedistal end of the offset guide may require adjusting a distance betweenthe patient's tibia and the patient's femur while rotating the cuttingblock relative to a distal surface of the patient's femur. In someembodiments, the method may require resecting a portion of the distalend of the patient's femur. In some embodiments, the method may requiredetaching the offset guide from the femoral cutting block and removingthe intramedullary orthopaedic surgical instrument from the opening inthe patient's femur.

According to another aspect of the disclosure, a method of performing anorthopaedic surgical procedure includes securing an offset guide to afemoral cutting block. The method also includes inserting an elongatedshaft of the offset guide into an opening defined in distal end of apatient's femur, wherein the elongated shaft extends along a firstlongitudinal axis. The method also includes attaching an offsetindicator to the distal end of the offset guide. The method alsoincludes rotating the offset indicator about a second longitudinal axisextending parallel to, and spaced apart from, the first longitudinalaxis to rotate the femoral cutting block about the first longitudinalaxis and determine an offset orientation for a prosthetic femoralcomponent.

In some embodiments, the method may require securing an intramedullaryorthopaedic surgical instrument to the offset guide such that the firstlongitudinal axis extends along the intramedullary orthopaedic surgicalinstrument. In some embodiments, rotating the offset indicator about thesecond longitudinal axis may require rotating a head plate of the offsetguide with the offset indicator about the second longitudinal axis, suchthat the offset guide may be secured to the femoral cutting block suchthat the femoral cutting block may be prevented from rotating relativeto the second longitudinal axis. In some embodiments, the method mayrequire attaching a first arm of a femoral positioning block to thefemoral cutting block. The method may require positioning a second armof the femoral positioning block on a proximal end of the patient'stibia such that a predetermined gap may be defined between the patient'stibia and the femoral cutting block. Rotating the offset indicator aboutthe second longitudinal axis may require adjusting a distance betweenthe patient's tibia and the patient's femur while rotating the cuttingblock relative to a distal surface of the patient's femur. In someembodiments, the method may require resecting a portion of the distalend of the patient's femur.

According to another aspect of the disclosure, a method of performing anorthopaedic surgical procedure includes securing an intramedullaryorthopaedic surgical instrument to an offset guide. The method alsoincludes securing the offset guide to a femoral cutting block. Themethod also includes inserting the intramedullary orthopaedic surgicalinstrument into an opening defined in a distal end of a patient's femur.The method also includes attaching a first arm of a femoral positioningblock to the femoral cutting block. The method also includes positioninga second arm of the femoral positioning block on a proximal end of thepatient's tibia such that a predetermined gap is defined between thepatient's tibia and the femoral cutting block. The method also includesrotating a distal end of the offset guide about a longitudinal axisextending through the intramedullary orthopaedic surgical instrument todetermine an offset orientation for a prosthetic femoral component.Rotating the distal end of the offset guide includes adjusting adistance between the patient's tibia and the patient's femur.

In some embodiments, the method may require attaching an offsetindicator to the distal end of the offset guide. Rotating the distal endof the offset guide may require rotating the offset indicator about asecond longitudinal axis extending parallel to, and spaced apart from,the longitudinal axis extending through the intramedullary orthopaedicsurgical instrument. In some embodiments securing the intramedullaryorthopaedic surgical instrument to the offset guide may requirepositioning a triangular-shaped connector of the offset guide into aplurality of slots defined in an inner surface of the intramedullaryorthopaedic surgical instrument, and engaging a sleeve of the offsetguide with the intramedullary orthopaedic surgical instrument to securethe intramedullary orthopaedic surgical instrument to offset guide. Insome embodiments, the inner surface of the intramedullary orthopaedicsurgical instrument may be threaded and engaging the sleeve of theoffset guide with the intramedullary orthopaedic surgical instrument mayrequire engaging a threaded outer surface of the sleeve with the innersurface of the intramedullary orthopaedic surgical instrument. In someembodiments, the method may require securing a stem stabilizer to a stemtrial to form the intramedullary orthopaedic surgical instrument.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description particularly refers to the following figures,in which:

FIG. 1 is an exploded perspective view of prosthetic components of anorthopaedic joint replacement system;

FIG. 2 is an exploded perspective view of a femoral cutting guideassembly of the orthopaedic joint replacement system;

FIG. 3 is a side elevation view of femoral cutting guide assembly ofFIG. 2 with the stem trial;

FIG. 4 is a distal perspective view of the femoral cutting guideassembly of FIG. 2 with the stem trial;

FIG. 5 illustrates a perspective view and exploded perspective view thefemoral cutting guide assembly and the stem trial of FIG. 3;

FIG. 6 is an exploded perspective view of the femoral offset guide ofFIG. 3;

FIG. 7 is an exploded elevation view of the femoral offset guide of FIG.6;

FIG. 8 is a perspective view of an offset indicator of orthopaedic jointreplacement system;

FIGS. 9-19 illustrate a number of steps of a surgical procedureutilizing the orthopaedic joint replacement system;

FIG. 20 is a perspective view of a stem stabilizer of FIG. 4;

FIG. 21 is an elevation view of the stem stabilizer of FIG. 20;

FIG. 22 is an exploded perspective view of another femoral cutting guideassembly of the orthopaedic joint replacement system; and

FIG. 23 is an exploded perspective view of the femoral cutting guideassembly of FIG. 22 with the stem stabilizer of FIGS. 18-19.

DETAILED DESCRIPTION OF THE DRAWINGS

While the concepts of the present disclosure are susceptible to variousmodifications and alternative forms, specific exemplary embodimentsthereof have been shown by way of example in the drawings and willherein be described in detail. It should be understood, however, thatthere is no intent to limit the concepts of the present disclosure tothe particular forms disclosed, but on the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the appended claims.

Terms representing anatomical references, such as anterior, posterior,medial, lateral, superior, inferior, etcetera, may be used throughoutthe specification in reference to the orthopaedic implants andorthopaedic surgical instruments described herein as well as inreference to the patient's natural anatomy. Such terms havewell-understood meanings in both the study of anatomy and the field oforthopaedics. Use of such anatomical reference terms in the writtendescription and claims is intended to be consistent with theirwell-understood meanings unless noted otherwise.

The exemplary embodiments of the present disclosure are described andillustrated below to encompass prosthetic knee joints and knee jointcomponents, as well as methods of implanting and reconstructing kneejoints. It will also be apparent to those of ordinary skill in the artthat the preferred embodiments discussed below are exemplary in natureand may be reconfigured without departing from the scope and spirit ofthe present invention. However, for clarity and precision, the exemplaryembodiments as discussed below may include optional steps, methods, andfeatures that one of ordinary skill should recognize as not being arequisite to fall within the scope of the present invention.

Referring now to FIG. 1, the orthopaedic joint replacement system 10includes a number of orthopaedic prosthetic components 12 and a numberof orthopaedic surgical instruments 14 (see, for example, FIG. 2) foruse in preparing the bone to receive one or more of the prostheticcomponents 12. What is meant herein by the term “orthopaedic surgicalinstrument” or “orthopaedic surgical instrument system” is a surgicaltool for use by a surgeon in performing an orthopaedic surgicalprocedure. As such, it should be appreciated that, as used herein, theterms “orthopaedic surgical instrument” and “orthopaedic surgicalinstruments” are distinct from orthopaedic prosthetic components orimplants, such as those shown in FIG. 1.

The prosthetic components 12 of the system 10 include a prostheticfemoral component 20 configured to be secured to a surgically-prepareddistal end of a patient's femur and a prosthetic tibial component 22configured to be secured to a surgically-prepared proximal end of thepatient's tibia. In the illustrative embodiment, the tibial component 22includes a tibial tray 24 and a prosthetic insert 26 configured toengage the femoral component 20 after implantation into a patient'sknee. It should be appreciated that the system 10 may include a numberof components 12 corresponding to patients having bones of varyingsizes. In that way, a surgeon will be able to select the components andother instruments that most-closely match the patient's bony anatomy.

As shown in FIG. 1, the femoral component 20 includes an anterior flange30 and a pair of condyles 32 extending away from the flange 30. A notch34, commonly called an intra-condylar notch, is defined between thecondyles 32. The condyles 32 define articulation surfaces 36 configuredto engage corresponding articulation surfaces 70 of the insert 26. Thefemoral component 20 also includes an elongated stem post 40, whichextends superiorly away from its backside surface 42. As described ingreater detail below, the femoral stem post 40 is configured to receiveone of a number of different stem components 44. In the illustrativeembodiment, a threaded bore 48, which is sized to receive acorresponding threaded shaft 50 of a stem component 44, is defined inthe stem post 40.

The tibial tray 24 is configured to be implanted into asurgically-prepared end of a patient's proximal tibia (not shown). Thetibial tray 24 includes a platform 58 having an elongated stem post 60extending inferiorly away from its inferior surface 62. The elongatedtibial stem post 60 is configured to receive one of a number ofdifferent stem components 44. Specifically, as can be seen in FIG. 1, athreaded bore 48, which is sized to receive a corresponding threadedshaft 50 of a stem component 44, is defined in the stem post 60.

The insert 26 is securable to the tibial tray 24. In particular, theinsert 26 may be snap-fit to the tibial tray 24. In such a way, theinsert 26 is fixed relative to the tibial tray 24 (i.e., it is notrotatable or moveable in the anterior/posterior or medial/lateraldirections). Although, in other embodiments, the tibial tray may besecured in a manner that allows it to rotate relative to the tibial tray24.

The insert 26 includes lateral and medial articulation surfaces 70. Thesurfaces 70 are configured to articulate with the correspondingarticulation surfaces 36 of the femoral component 20. Specifically, thefemoral component 20 is configured to be implanted into asurgically-prepared distal end of the patient's femur (not shown), andis configured to emulate the configuration of the patient's naturalfemoral condyles. As such, the articulation surfaces 36 of the femoralcomponent 20 are configured (e.g., curved) in a manner which mimics thecondyles of the natural femur.

As shown in FIG. 1, the stem components 44 of the system 10 includeelongated stems 80, which are configured to be attached to either of thecomponents 20, 22. Each elongated stem 80 extends from the threadedshaft 50 at one end to a pointed tip 82 at the opposite end. Each stemalso includes a ribbed outer surface 84 extending from the pointed tip82 toward the threaded shaft 50. A plurality of substantially planarsurfaces 86 are positioned around the outer circumference of the stem 80adjacent to the shaft 50. The surfaces 86 are sized and positioned toreceive the end of a wrench or other installation tool so that the stem80 may be rotated into tight engagement with one of the threaded bores48.

In the illustrative embodiment, the prosthetic components 12 alsoinclude a plurality of offset adapters 90, 92 configured to be attachedto the components 20, 22. As shown in FIG. 1, the adapter 90 isconfigured to offset the longitudinal axis of the elongated stem 80 fromthe longitudinal axis of the stem post 60 of the tibial tray 24 by apredetermined amount. Similarly, the adapter 92 is configured offset thelongitudinal axis of the elongated stem 80 from the longitudinal axis ofthe stem post 40 of the femoral component 20. Each of the adapters 90,92 includes a threaded shaft 50 configured to be received in thethreaded bore 48 of either of the components 20, 22. Each of theadapters 90, 92 also includes a threaded bore 48 at its opposite end,which is sized to receive a threaded shaft 50 of one of the elongatedstems 80. In the illustrative embodiment, a locking nut 100 ispositioned on the threaded shaft 50 of each of the adapters 90, 92. Thelocking nut 100 may be typed against the surface of the stem post ofeach component to secure the adapter thereto.

The components of the knee prosthesis 10 that engage the natural bone,such as the femoral component 20, the tibial tray 24, and the stemcomponents 44, may be constructed with an implant-grade biocompatiblemetal, although other materials may also be used. Examples of suchmetals include cobalt, including cobalt alloys such as a cobalt chromealloy, titanium, including titanium alloys such as a Ti6Al4V alloy, andstainless steel. Such a metallic components may also be coated with asurface treatment, such as hydroxyapatite, to enhance biocompatibility.Moreover, the surfaces of the metallic components that engage thenatural bone may be textured to facilitate securing the components tothe bone. Such surfaces may also be porous coated to promote boneingrowth for permanent fixation.

The insert 26 may be constructed with a material that allows for smootharticulation between the insert 26 and the femoral component 20, such asa polymeric material. One such polymeric material is polyethylene suchas ultrahigh molecular weight polyethylene (UHMWPE).

Referring now to FIG. 2, the system 10 includes a number of surgicalinstruments 14. The surgical instruments include a base cutting block212 configured for use on a femur of a patient and an offset guideassembly 214 configured to be secured to the base cutting block 212. Inthe illustrative embodiment, the offset guide assembly is an“intramedullary orthopedic surgical instrument,” which is a surgicaltool configured to be at least partially positioned in the medullarycanal of the patient's femur during the orthopedic surgical procedure.As shown in FIG. 2, the offset guide assembly 214 includes an offsetguide 216 and a stem stabilizer 218 configured to be attached to a stemtrial 220 (see FIG. 5). It should be appreciated that an assemblyincluding the offset guide 216 and the stem stabilizer 218 without thestem trial may be an intramedullary orthopedic surgical instrument;similarly, an assembly including the stem stabilizer 218 and the stemtrial 220 may be an intramedullary orthopedic surgical instrument.

The base cutting block 212 includes a base plate 222, which is formedfrom a metallic material, such as, for example, a stainless steel orcobalt chrome alloy. The base plate includes a distal surface 224 and aproximal surface 226 that is positioned opposite the distal surface. Apassageway 228 extends through the surfaces 224, 226, and the passageway228 is sized to permit the passage of the offset guide assembly 214, asshown in FIG. 2. The base cutting block 212 includes a number offixation pin guide holes 230, which are sized to receive fixation pins262 to secure the base cutting block to the patient's femur.

The base cutting block 212 includes a number of cutting guides 232,which may be used during the orthopedic surgical procedure to resect aportion of a patient's femur. In the illustrative embodiment, each ofthe cutting guides 232 is a posterior cutting guide for use in guidingthe resection of a posterior surface of the patient's femur. The basecutting block 212 also includes a posterior chamfer cutting guide 234,which may be used to guide the resection of a posterior chamfer surfaceof the patient's femur. Each guide includes an elongated slot that issized to receive a cutting saw blade of a surgical saw or other device.The base cutting block 212 also includes a mounting platform 236, whichis configured to receive modular cutting guide blocks that may beselectively secured to the base cutting block 212, as described ingreater detail below.

As described above, the offset guide assembly 214 may be secured to thebase cutting block 212. As shown in FIG. 2, the base cutting block 212includes a pair of locking tabs 240, 242 that are pivotally coupled tothe base plate 222. Each of the tabs 240, 242 is positioned in anaperture 244 positioned on each side of the passageway 228. The tabs240, 242 are coupled to the base plate 222 via pivot joint 250, whichpermits the locking tabs 240, 242 to rotate between a locked positionand an unlocked position. In the unlocked position, an ear 252 of thelocking tab faces away from the passageway 228, as shown in FIG. 2. Inthe locked position, the ear 252 faces toward the passageway 228. Whenthe offset guide 216 is positioned as shown in FIG. 4, the ears 252 ofthe locking tabs 240, 242 are positioned over retaining flanges 254 ofthe offset guide 216. In that way, the retaining flanges 254 arecaptured between the locking tabs 240, 242 and a bottom wall 260 of theplate 222.

Referring now to FIG. 3, the distal surface 224 of the cutting block 212defines an imaginary plane 270, and a longitudinal axis 272 extendsalong the offset guide assembly 214 through the stem trial 220. In theillustrative embodiment, the axis 272 corresponds to the longitudinalaxis of the elongated stem 80 of the femoral prosthetic assembly. Anoblique angle 274 is defined between the axis 272 and the imaginaryplane 270, which corresponds to the angle between the elongated stem 80and the femoral component 20 in the femoral prosthetic assembly.

As shown in FIG. 4, the offset guide assembly 214 includes an aperture280 that is formed at its distal end 282. The aperture 280 extendsinwardly from an annular surface 284 to a bottom surface 286. Theannular surface 284 includes a number of indicia 288, and, as shown inFIG. 3, also extends at an oblique angle relative to the distal surface224 of the cutting block 212, orthogonal to the longitudinal axis 272.In the illustrative embodiment, the indicia 288 include lines etched inthe surface 284. As described in greater detail below, the indicia 288may be used to provide the surgeon with an indication of the offsetorientation during a surgical procedure. An alignment groove 290, whichorients an offset indicator 292 (see FIG. 8), is defined in the annularsurface 284. The offset guide assembly 214 also includes a socket 294that is defined in the bottom surface 286 of the aperture 280. Thesocket 294 is sized to receive a hex end of a driver 296 (see FIG. 11),as described in greater detail below.

Referring now to FIG. 5, the offset guide assembly 214 includes theoffset guide 216, the stem stabilizer 218, which may be selectivelyattached to the offset guide 216, and one of a number of stem trials220, which vary in length and diameter and may be selectively attachedto the stabilizer 218. In the illustrative embodiment, the guide 216,stabilizer 218, and stem trial 220 are formed from metallic materials,such as, for example stainless steel or cobalt chrome alloy. The offsetguide 216 includes a mounting bracket 300 and an adapter body 302 thatis pivotally coupled to the mounting bracket 300. The mounting bracket300 includes the retaining flanges 254, which are positioned at each ofits ends 304, 306 and are sized to receive the ears 252 of the lockingtabs 240, 242. The mounting bracket 300 also includes a distal surface308 that extends parallel to the distal surface 224 of the cutting block212 when the offset guide assembly 214 is attached to the cutting block212.

The offset guide 216 has a proximal end 310 that includes a connectorhaving a triangular shape. The stabilizer 218 has a distal opening 312that is sized to receive the proximal end 310. As shown in FIG. 5 and ingreater detail in FIGS. 20-21, the stabilizer 218 includes an inner wall316 that extends inwardly from the distal opening 312. The inner wall316 is threaded and has a plurality of longitudinal slots 318 defined inthe threads. Each slot 318 is sized to receive a tip of thetriangular-shaped connector 310.

To assemble the offset guide 216 to the stem stabilizer 218, the surgeonmay locate the proximal end 310 in the opening 312 and tighten thethreads of the offset guide 216, as described in greater detail below.The stabilizer 218 also has a threaded proximal opening (not shown) thatis sized to receive the threaded distal end 314 of the stem trial 220.

Referring now to FIGS. 6-7, the adapter body 302 of the offset guide 216includes the annular surface 284 described above. The annular surface284 is included on a head plate 320 of the adaptor body 302. A post 322extends away from the head plate 320, and the adapter body 302 includesa lower shell 324 that is connected to, but offset from, the post 322.The post 322 includes an annular groove 326 that is defined in its outersurface 328. In the illustrative embodiment, the offset guide 216includes a pair of pins 330 that extend through the mounting bracket 300and are positioned in the annular groove 326 to secure the adapter body302 to the mounting bracket 300. The smooth outer surfaces of the pins330 permit the cylindrical post 322 to rotate about its longitudinalaxis 332 relative to the mounting bracket 300. As shown in FIG. 6, thelongitudinal axis 332 of the post 322 is offset from, and extendsparallel to, the longitudinal axis 272 of the offset guide assembly 214.It should be appreciated that the same oblique angle 274 described abovein regard to FIG. 3 is defined between the longitudinal axis 332 and theimaginary plane 270.

The lower shell 324 of the adapter body 302 has a distal-facing aperture334. The offset guide 216 includes an intermediate housing or sleeve 336that is positioned below the lower shell 324. The housing 336 has apassageway 338 that is aligned with the aperture 334 of the lower shell324. As shown in FIGS. 6-7, the triangular-shaped proximal end 310 isattached to an elongated shaft 340 that is sized to be positioned in thepassageway 338 and the aperture 334. The elongated shaft 340 has anannular groove 342 positioned adjacent to its distal end 344. A pair ofpins 350 extend through the lower shell 324 and into the annular groove342. The smooth outer surfaces of the pins 350 permit the elongatedshaft 340 (and hence the proximal end 310) to rotate about thelongitudinal axis 272 relative to the adapter body 302. The housing 336and the elongated shaft 340 are configured to permit limited axialmovement along the longitudinal axis 272 relative to the mountingbracket 300.

The sleeve 336 also includes a threaded outer surface 352 thatpositioned adjacent to the connector end 310 of the elongated shaft 340.As described above, the threaded outer surface 352 of the guide 216 isconfigured to engage the threaded inner wall 316 of the stabilizer 316to secure the stabilizer 316 on the guide 216. As described above, thestabilizer 316 is first positioned on the connector end 310 of the guide216 with the tips of connector positioned in the elongated slots 318 ofthe stabilizer 218. The sleeve 336 is then moved along the axis 272toward the connector end 310 to engage its threaded outer surface 352with the threaded inner wall 316 of the stabilizer 316. The sleeve 336may then be threaded into the stabilizer 218 to secure the partstogether.

Referring now to FIG. 8, the offset indicator 292 includes a centralpost 360 that is connected to a conical flange 362. The post 360includes a plug 364 that extends downwardly from the flange 362 to theend 366 of the indicator 292. The plug 364 is sized to be positioned inthe distal aperture 280 of the offset guide assembly 214 and includes analignment tab 368 that is sized to be received in the groove 290 definedin the offset guide assembly 214.

The offset indicator 292 has a passageway 370 that extends through thepost 360. The passageway 370 is sized to receive the hex end of thedriver 296. In the illustrative embodiment, the passageway 370 isdefined by a smooth cylindrical surface 372 such that the offsetindicator 292 does not engage the driver 296 and rotate directly withit. Instead, the engagement between tab 368 of the indicator 292 and thegroove 290 of the offset guide 216 causes the offset indicator to rotatewith the adaptor body 302 of the offset guide.

As shown in FIG. 8, the conical flange 362 has a plurality of indicia380 located on its upper surface 382. In the illustrative embodiment,the indicia 380 include etched lines 384 and numbers 386 associated witheach etched line 384. The numbers 386 correspond to predetermined offsetorientations of the offset adaptor 92 for the femoral component 20. Whenan etched line 384 of the indicator 292 is aligned with an etched mark390 on the mounting bracket 300 (see FIGS. 12A and B), the surgeonidentifies the number 386 associated with that line 384. The number isthen used to set the final offset orientations of the offset adaptor 92.It should be appreciated that other indicia may be used to inform thesurgeon of the offset orientation.

As described above, the instruments 14 may be used to surgically preparea patient's femur to receive a prosthetic femoral component 20 and oneof the stem components 44. In the illustrative embodiment, theinstruments 14 may be used in a revision procedure in which a primaryimplant has been removed from a distal end of the patient's femur. Asshown in FIG. 9, the distal end 400 of a patient's femur 402 in arevision procedure includes a plurality of surfaces 404 that had beenpreviously-shaped to receive the primary implant. During a revisionprocedure, the surfaces 404 are resected to prepare the distal end 400to receive the prosthetic femoral component 20. FIGS. 9-19 illustrate anumber of exemplary steps of a procedure for surgically-preparing thedistal end 400 during a revision procedure. It should be appreciatedthat any surgical procedure may include additional or fewer stepsdepending on the state of the patient's bony anatomy and the preferencesof the surgeon.

Referring now to FIG. 9, the distal end 400 of the patient's femur 402includes an opening 406 defined in one of the surfaces 404. The opening406 permits the surgeon to access the intramedullary canal of thepatient's femur 402. To resect the patient's bone, surgeon may begin byassembling the offset guide 216, a stem stabilizer 218, and a stem trial220 to form the offset guide assembly 214 shown in FIG. 9. By utilizingthe locking tabs 240, 242, the surgeon may attach the offset guideassembly 214 to the base cutting block 212.

With the offset guide assembly 214 attached to the base cutting block212, surgeon may align the proximal tip of the stem trial 220 with theopening 406 in the patient's femur 402, as shown in FIG. 9. The surgeonmay then advance the stem trial 220 into the opening 406, as indicatedby arrow 410. The surgeon may continue to move the base cutting block212 and the offset guide assembly 214 in the direction indicated byarrow 410 to position the base cutting block 212 in contact with thedistal end 400 of the patient's femur 402, as shown in FIG. 9A. With thebase cutting block 212 positioned as shown in FIG. 9A, the surgeon mayplace the knee joint in extension and evaluate the extension space.

After returning the joint to flexion as shown in FIG. 10, the surgeonmay attach an anterior cutting block 420 to the mounting platform 236 ofthe base cutting block 212. The anterior cutting block 420 includes acutting guide 422 that is sized to receive a cutting blade of a surgicalsaw. To assess the balance of the knee joint, the surgeon may positionalignment tool 424 in the cutting guide 422 such that a probe tip 426 ofthe tool 424 contacts the patient's femur 402. The alignment tool 424may be used to assess the anterior resection performed using theanterior cutting block 420.

The surgeon may attach a balancing block 428 to the base cutting block212, as shown in FIG. 10. The balancing block includes a handle and anupper arm 430 and lower arm 432 extending outwardly from the handle. Theupper arm 430 is configured to be attached to the base cutting block212, and the lower arm 432 includes a plate 434 sized to be positionedon a surgically-prepared proximal end 436 of a patient's tibia 438 or ona tibial base plate (if any) attached to the patient's tibia. As shownin FIG. 10, the upper arm 430 is spaced a predefined distance from thelower arm 432 such that the proximal end 436 of the patient's tibia 438is spaced a predetermined distance from the cutting block 212.

As shown in FIG. 11, the surgeon may attach the offset indicator 292 toa driver 296 and then advance the offset indicator 292 into the aperture280 defined in the offset guide assembly 214. As described above, thepassageway 370 of the offset indicator 292 is sized to permit thepassage of the hex head of the driver 296, thereby allowing the hex headto enter the socket 294 defined at the base of the aperture 280. Thesurgeon may then rotate the driver 296 as indicated by arrows 440.

The engagement between the driver 296 and the offset guide 216 causesthe adapter body 302 to rotate about its axis 332 with the driver 296.As the adapter body 302 rotates, the engagement between the stemstabilizer 218 and the patient's femur 402 causes the adapter body 302and the cutting block 212 to rotate about the axis 272. This combinedrotation causes the cutting block 212 to be repositioned on the distalend 400 of the patient's femur 402. As the cutting block 212 rotatesrelative to the distal end 400 of the patient's femur 402, the block 428maintains the cutting block 212 in position relative to the tibia 438,and the distance (and position) between the distal end 400 of thepatient's femur 402 and the proximal end 436 is adjusted.

With the balancing block 428 still attached to the cutting block 212,the surgeon may continue to assess ligament tension while at the sametime determining the offset orientation. When the desired offset hasbeen achieved, the surgeon may insert one or more fixation pins 450 (seeFIG. 13) into the patient's femur 402 through the guide holes 230defined in the cutting block 212. As shown in FIGS. 12A and 12B, thesurgeon may note the preliminary offset position from the alignment ofthe etched line 384 and associated number 386 on the offset indicator292 with the etched mark 390 on the mounting bracket 300.

Referring now to FIGS. 18-19, a surgeon may evaluate ligament tensionduring the surgical procedure using other methods. For example, as shownin FIG. 18, the surgeon may utilize visual landmarks on the patient'sfemur 402 and tibia 438 to determine the desired offset orientation. Asshown in FIG. 19 the surgeon may utilize a spacer instrument 542, whichincludes a distal end 544 configured to engage the cutting block 212 andthe patient's tibia 438 (or tibial base plate 546) to evaluate ligamenttension and set the offset orientation.

As shown in FIG. 13, the surgeon may then use the anterior cutting block420 to guide the surgical saw 442 during the performance of an anteriorresection. After performing the anterior resection, the surgeon mayremove the anterior cutting block 420 from the base cutting block 212.The surgeon may also utilize the cutting guides 232 of the base cuttingblock 212 to perform a posterior resection of the patient's femur 402.

Referring now to FIGS. 14-15, the surgeon may utilize an impactionhandle 452 to remove the offset guide assembly 214 from the distal end400 of the patient's femur 402. The impaction handle 452 includes anelongated body 454. The elongated body 454 is sized and shaped to begripped by a surgeon during use. The impaction handle 452 also includesa proximal post 458 that extends from the end 456 of the elongated body454. The proximal post 458 includes a tip (not shown) sized to bepositioned in the aperture 280 of the alignment guide assembly 214.

The impaction handle 452 includes an attachment mechanism 460 configuredto selectively secure the offset guide assembly 214 to the impactionhandle 452. In the illustrative embodiment the attachment mechanism 460includes a lever arm 462 configured to pivot relative to the proximalpost 458. The lever arm 462 includes a locking flange 464 that extendstoward tip of the post 458. When the lever arm 462 is pivoted in thedirection indicated by arrow 466 in FIG. 15, the locking flange 464 isadvanced away from the tip. The lever arm 462 also includes a tab 468that extends in the direction opposite the locking flange 464.

The attachment mechanism 460 includes a bracket 470 that is configuredto slide relative to the post 458 and the elongated body 454. Thebracket 470 is illustratively L-shaped and includes a flange 478 thatextends away from the proximal post 458. The flange 478 is connected toa slide plate 474 that extends along the post 458. As shown in FIGS. 14and 15, the slide plate 474 has an oblong slot 476 defined therein, andthe tab 468 is positioned in the slot 476.

As shown in FIG. 15, the locking flange 464 engages the head plate 320of the offset guide assembly 214 to secure the assembly to the handle452. The surgeon may grip the elongated body 454 to pull the assembly214 away from the base cutting block 212 and withdraw the stemstabilizer 218 and stem trial 220 from the patient's femur 402.

Referring now to FIGS. 16A and 16B, the surgeon may attach a notchcutting block 490 to the mounting platform 236 of the base cutting block212. The notch cutting block 490 includes a notch cutting guide 492 thatis sized to receive a cutting blade of a surgical saw. The notch cuttingblock 490 also includes a number of distal cutting guides 494 configuredto guide the resection of the distal surfaces of the patient's femur402. With the notch cutting block attached to the base cutting block212, the surgeon may utilize the saw 442 to make the distal and notchresections of the patient's femur.

As shown in FIG. 17, surgeon may also utilize a reaming guide 500 withthe cutting block 212. To do so, surgeon positions the mounting bracket300 of the reaming guide 500 in the passageway 228 and operates thelocking tabs 240, 242 to secure the reaming guide 500 to the cuttingblock 212 as shown in FIG. 17. Surgeon may then use one or more reamersto enlarge the opening 406 to receive the offset adapter 92 and the stemcomponent 44 of the femoral prosthetic assembly.

Referring now to FIGS. 22-23, another embodiment of a base cutting block612 and an offset guide 616 configured to be secured to the base cuttingblock 612. The cutting block 612 and the offset guide 616 are similar tothe cutting block 212 and the offset guide 616 described above in regardto FIGS. 1-21 and the same reference numbers will be used to identifysimilar features. The base cutting block 612 includes a base plate 622,which is formed from a metallic material, such as, for example, astainless steel or cobalt chrome alloy. The base plate includes a distalsurface 224 and a proximal surface 226 that is positioned opposite thedistal surface. A passageway 628 extends through the surfaces 224, 226.The base cutting block 612 includes a number of fixation pin guide holes230, which are sized to receive fixation pins 262 to secure the basecutting block to the patient's femur.

The base cutting block 612 includes a number of cutting guides 232,which may be used during the orthopedic surgical procedure to resect aportion of a patient's femur. In the illustrative embodiment, each ofthe cutting guides 232 is a posterior cutting guide for use in guidingthe resection of a posterior surface of the patient's femur. The basecutting block 212 also includes a posterior chamfer cutting guide 234,which may be used to guide the resection of a posterior chamfer surfaceof the patient's femur. Each guide includes an elongated slot that issized to receive a cutting saw blade of a surgical saw or other device.The base cutting block 612 also includes a mounting platform 236, whichis configured to receive modular cutting guide blocks that may beselectively secured to the base cutting block 212, as described ingreater detail below.

The offset guide 616 includes a mounting bracket 700 and an adapter body302 that is pivotally coupled to the mounting bracket 700. The mountingbracket 700 includes the retaining flanges 754, which are positioned ateach of its ends 704, 706. The mounting bracket 700 includes a pair ofretained fasteners 756 (illustratively, screws), which are secured toeach retaining flange 754, and are received in a pair of threaded bores758 defined in the cutting block 612 to secure the offset guide 616 tothe cutting block 612. It should be appreciated that such fasteners maybe retained using washers, various hole diameters, and flange/aperturesizing.

The offset guide 616 has a proximal end 310 that includes a connectorhaving a triangular shape, and, as shown in FIG. 23, the stabilizer 218is configured to be mounted on the connector end 310, as describedabove. To assemble the offset guide 216 to the stem stabilizer 218, thesurgeon may locate the proximal end 310 in the opening 312 and tightenthe threads of the offset guide 216, as described in greater detailbelow. The stabilizer 218 also has a threaded proximal opening 760 thatis sized to receive the threaded distal end 314 of the stem trial 220.

While the foregoing exemplary embodiments have been described to have aseparable tibial tray and a tibial tray insert, it is to be understoodthat the tibial tray may include condyle receiver bearing surfaces thatobviate the need for a separate tibial tray insert.

Following from the above description and invention summaries, it shouldbe apparent to those of ordinary skill in the art that, while themethods and apparatuses herein described constitute exemplaryembodiments of the present invention, the invention contained herein isnot limited to this precise embodiment and that changes may be made tosuch embodiments without departing from the scope of the invention asdefined by the claims. Additionally, it is to be understood that theinvention is defined by the claims and it is not intended that anylimitations or elements describing the exemplary embodiments set forthherein are to be incorporated into the interpretation of any claimelement unless such limitation or element is explicitly stated.Likewise, it is to be understood that it is not necessary to meet any orall of the identified advantages or objects of the invention disclosedherein in order to fall within the scope of any claims, since theinvention is defined by the claims and since inherent and/or unforeseenadvantages of the present invention may exist even though they may nothave been explicitly discussed herein.

The invention claimed is:
 1. A method of performing an orthopaedicsurgical procedure, the method comprising: aligning a distal end of anintramedullary orthopaedic surgical instrument with a proximal end of anoffset guide, positioning a connector at the proximal end of the offsetguide in an opening defined in the distal end of the intramedullaryorthopaedic surgical instrument to prevent relative rotational movementbetween the proximal end of the offset guide and the intramedullaryorthopaedic surgical instrument thereby advancing the intramedullaryorthopaedic surgical instrument over the connector, engaging a sleevewith the intramedullary orthopaedic surgical instrument to secure theintramedullary orthopaedic surgical instrument to the offset guide,inserting the intramedullary orthopaedic surgical instrument into anopening defined in a distal end of a patient's femur, rotating a distalend of the offset guide about a longitudinal axis extending through theintramedullary orthopaedic surgical instrument to determine an offsetorientation for a prosthetic femoral component, securing the distal endof the offset guide to a femoral cutting block including a plurality ofcutting slots, wherein rotating the distal end of the offset guideincludes rotating the femoral cutting block relative to a distal surfaceof the patient's femur, and attaching an offset indicator to the distalend of the offset guide, wherein rotating the distal end of the offsetguide includes rotating the offset indicator about a second longitudinalaxis extending parallel to, and spaced apart from, the longitudinal axisextending through the intramedullary orthopaedic surgical instrument. 2.The method of claim 1, wherein engaging the sleeve with theintramedullary orthopaedic surgical instrument includes advancing thesleeve toward the proximal end of the offset guide and engaging athreaded outer surface of the sleeve with a threaded inner surface ofthe intramedullary orthopaedic surgical instrument.
 3. The method ofclaim 2, wherein positioning the connector at the proximal end of theoffset guide in the opening defined in the distal end of theintramedullary orthopaedic surgical instrument includes positioning atriangular-shaped connector into a plurality of slots defined in thethreaded inner surface of the intramedullary orthopaedic surgicalinstrument.
 4. The method of claim 1, further comprising securing a stemstabilizer to a stem trial to form the intramedullary orthopaedicsurgical instrument.
 5. The method of claim 1, further comprising:attaching a first arm of a femoral positioning block to the femoralcutting block, and positioning a second arm of the femoral positioningblock on a proximal end of the patient's tibia such that a predeterminedgap is defined between the patient's tibia and the femoral cuttingblock, wherein rotating the distal end of the offset guide includesadjusting a distance between the patient's tibia and the patient's femurwhile rotating the femoral cutting block relative to a distal surface ofthe patient's femur.
 6. The method of claim 1, further comprisingresecting a portion of the distal end of the patient's femur.
 7. Themethod of claim 6, further comprising detaching the offset guide fromthe femoral cutting block and removing the intramedullary orthopaedicsurgical instrument from the opening in the distal end of the patient'sfemur.
 8. A method of performing an orthopaedic surgical procedure, themethod comprising: securing an offset guide to a femoral cutting block,inserting an elongated shaft of the offset guide into an opening definedin a distal end of a patient's femur, the elongated shaft extendingalong a first longitudinal axis, attaching an offset indicator to adistal end of the offset guide, rotating the offset indicator about asecond longitudinal axis extending parallel to, and spaced apart from,the first longitudinal axis to rotate the femoral cutting block aboutthe first longitudinal axis and determine an offset orientation for aprosthetic femoral component, attaching a first arm of a femoralpositioning block to the femoral cutting block, and positioning a secondarm of the femoral positioning block on a proximal end of the patient'stibia such that a predetermined gap is defined between the patient'stibia and the femoral cutting block, wherein rotating the offsetindicator about the second longitudinal axis includes adjusting adistance between the patient's tibia and the patient's femur whilerotating the femoral cutting block relative to a distal surface of thepatient's femur.
 9. The method of claim 8, further comprising securingan intramedullary orthopaedic surgical instrument to the offset guidesuch that the first longitudinal axis extends along the intramedullaryorthopaedic surgical instrument.
 10. The method of claim 9, whereinrotating the offset indicator about the second longitudinal axisincludes rotating a head plate of the offset guide with the offsetindicator about the second longitudinal axis, and the offset guide issecured to the femoral cutting block such that the femoral cutting blockis prevented from rotating relative to the second longitudinal axis. 11.The method of claim 8, further comprising resecting a portion of thedistal end of the patient's femur.
 12. A method of performing anorthopaedic surgical procedure, the method comprising: securing anintramedullary orthopaedic surgical instrument to an offset guide,securing the offset guide to a femoral cutting block, inserting theintramedullary orthopaedic surgical instrument into an opening definedin a distal end of a patient's femur, attaching a first arm of a femoralpositioning block to the femoral cutting block, positioning a second armof the femoral positioning block on a proximal end of the patient'stibia such that a predetermined gap is defined between the patient'stibia and the femoral cutting block, rotating a distal end of the offsetguide about a longitudinal axis extending through the intramedullaryorthopaedic surgical instrument to determine an offset orientation for aprosthetic femoral component, wherein rotating the distal end of theoffset guide includes adjusting a distance between the patient's tibiaand the patient's femur, and attaching an offset indicator to the distalend of the offset guide, wherein rotating the distal end of the offsetguide includes rotating the offset indicator about a second longitudinalaxis extending parallel to, and spaced apart from, the longitudinal axisextending through the intramedullary orthopaedic surgical instrument.13. The method of claim 12, wherein securing the intramedullaryorthopaedic surgical instrument to the offset guide includes:positioning a triangular-shaped connector of the offset guide into aplurality of slots defined in an inner surface of the intramedullaryorthopaedic surgical instrument, and engaging a sleeve of the offsetguide with the intramedullary orthopaedic surgical instrument to securethe intramedullary orthopaedic surgical instrument to offset guide. 14.The method of claim 13, wherein the inner surface of the intramedullaryorthopaedic surgical instrument is threaded and engaging the sleeve ofthe offset guide with the intramedullary orthopaedic surgical instrumentincludes engaging a threaded outer surface of the sleeve with thethreaded inner surface of the intramedullary orthopaedic surgicalinstrument.
 15. The method of claim 14, further comprising securing astem stabilizer to a stem trial to form the intramedullary orthopaedicsurgical instrument.